Displacement detecting apparatus, displacement detecting method and substrate processing apparatus

ABSTRACT

A displacement detecting apparatus according to the invention comprises: a mover which moves and positions a positioning object; an imager which images an image including an imaging object which is the positioning object or an object displacing integrally with the positioning object as the positioning object is displaced; and a displacement detector which detects the imaging object from the image imaged by the imager and detects a displacement of the positioning object based on the position of the imaging object detected in the image, wherein the displacement detector obtains a displacement amount of the positioning object with respect to a predetermined reference position from a value obtained by multiplying a distance between the position of the imaging object and the reference position in the image by a coefficient determined according to size of the imaging object in the image.

CROSS REFERENCE TO RELATED APPLICATION

The disclosure of Japanese Patent Application No. 2016-160979 filed onAug. 19, 2016 including specification, drawings and claims isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to a technique for detecting a displacement of amovable positioning object with respect to a reference position.

2. Description of the Related Art

As a technique for detecting the position of a movable positioningobject or determining whether or not the positioning object ispositioned at a designated position, the positioning object is imagedusing an imager such as a camera and the position of the positioningobject in an image is detected by an image analysis. For example, in atechnique described in JP 2015-152475A, a processing nozzle configuredto be movable with respect to a substrate and discharge a liquid or thelike is a positioning object. A displacement amount in an actual spaceis approximately obtained by multiplying a displacement amount of theprocessing nozzle in an image imaged by the camera by a proportionalitycoefficient corresponding to an imaging magnification.

In a substrate processing apparatus as in the above conventionaltechnique, whether or not a processing nozzle as a positioning object issatisfactorily positioned is determined based on whether or not adisplacement amount of the positioning object is within an allowablerange when a proper position designated in advance is a referenceposition. The displacement amount evaluated at this time has to benaturally that in an actual space.

On the other hand, a positional displacement amount of the positioningobject detected in the image, i.e. a distance between the positioningobject and the reference position, does not necessary coincide with thedisplacement amount in the actual space. Specifically, due to a movementmode of the positioning object and a positional relationship with animager, there is a nonlinear relationship between the magnitude of thepositional displacement amount detected in the image and thedisplacement amount in the actual space.

For example, even if the displacement amount in the actual space is thesame, the displacement in the image is relatively large when thepositioning object is relatively close to the imager, whereas thedisplacement in the image is small when the positioning object is moredistant from the imager. Thus, it is necessary to make a coefficient forconverting the displacement amount in the image into the displacementamount in the actual space different depending on the distance betweenthe positioning object and the imager. As just described, in a methodfor obtaining a displacement amount in an actual space by multiplying adisplacement amount in an image by a constant proportionalitycoefficient, detection accuracy is possibly insufficient.

SUMMARY OF THE INVENTION

This invention was developed in view of the above problem and an objectthereof is to provide a technique capable of detecting a displacement ofa positioning object with respect to a reference position in an actualspace with excellent accuracy.

To achieve the above object, one aspect of this invention is directed toa displacement detecting apparatus. The displacement detecting apparatuscomprises: a mover which moves and positions a positioning object; animager which images an image including an imaging object which is thepositioning object or an object displacing integrally with thepositioning object as the positioning object is displaced; and adisplacement detector which detects the imaging object from the imageimaged by the imager and detects a displacement of the positioningobject based on the position of the imaging object detected in theimage, wherein the displacement detector obtains a displacement amountof the positioning object with respect to a predetermined referenceposition from a value obtained by multiplying a distance between theposition of the imaging object and the reference position in the imageby a coefficient determined according to size of the imaging object inthe image.

Further, another aspect of this invention is directed to a displacementdetecting method for detecting a displacement of a positioning objectmoved and positioned by a mover. The displacement detecting methodcomprises: imaging an image including an imaging object which is thepositioning object or an object displacing integrally with thepositioning object as the positioning object is displaced; detecting theimaging object from the image; and detecting a displacement of thepositioning object with respective to a predetermined reference positionbased on the position of the imaging object detected in the image,wherein a displacement amount of the positioning object is obtained froma value obtained by multiplying a distance between the position of theimaging object and the reference position in the image by a coefficientdetermined according to size of the imaging object in the image.

In the inventions thus configured, the displacement amount of thepositioning object in an actual space can be accurately obtained withoutdepending on a distance between the imaging object and the imager indealing with a problem that a relationship of the displacement amount inthe image and the displacement amount in the actual space changesdepending on the distance between the imaging object and the imager.This is for the following reason.

When the imaging object is close to the imager, an area taken up by theimaging object in the image is relatively large and a displacement inthe image when the imaging object moves is relatively large. On theother hand, when the imaging object is distant from the imager, theimaging object is reflected to be relatively small in the image and amovement in the actual space also appears to be small in the image. Inother words, even if the displacement amount in the image expressed, forexample, by a pixel number is the same, the displacement amount in theactual space is larger when the imaging object is distant from theimager than when the imaging object is close to the imager.

Accordingly, in the invention, the displacement amount of the imagingobject in the actual space is obtained based on the value obtained bymultiplying the distance between the position of the imaging objectdetected in the image and the reference position by the coefficientdetermined according to the size of the imaging object in the image. Bydoing so, in converting the displacement amount detected in the imageinto the displacement amount in the actual space, the coefficientaccording to the size of the imaging object in the image, i.e. thedistance between the imaging object and the imager can be applied. Byperforming conversion with the distance between the imaging object andthe imager reflected on the coefficient in this way, the displacementamount of the positioning object in the actual space can be accuratelyobtained by suppressing a calculation error due to a difference indistance.

Further, another aspect of this invention is directed to a substrateprocessing apparatus. The substrate processing apparatus comprises: aholder which holds a work to be processed; a nozzle which discharges andsupplies a fluid to the work; and the displacement detecting apparatusof the above configuration using the nozzle as the positioning object.In such an invention, since the position of the nozzle with respect tothe work is accurately obtained from an image, the work can be processedwith the position of the nozzle properly managed and the process cansatisfactorily proceed.

As described above, in the invention, the distance between the imagingobject and the imager is reflected on the coefficient in converting thedisplacement amount in the image into the displacement amount in theactual space. By doing so, a calculation error due to a difference indistance can be suppressed and the displacement amount of thepositioning object in the actual space can be accurately obtained.

The above and further objects and novel features of the invention willmore fully appear from the following detailed description when the sameis read in connection with the accompanying drawing. It is to beexpressly understood, however, that the drawing is for purpose ofillustration only and is not intended as a definition of the limits ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing showing the structure of a substrateprocessing system according to an embodiment of the invention.

FIG. 2 is a plan view showing the structure of one substrate processingunit.

FIG. 3 is a drawing showing the cross section of FIG. 2 taken along thearrow A-A and the structure of the controller of the substrateprocessing unit.

FIG. 4 is a flow chart showing the operation of the substrate processingunit.

FIG. 5 is a schematic drawing showing an example of an image which isobtained by imaging inside the chamber.

FIG. 6 is a drawing showing an example of an image obtained by imagingthe nozzle.

FIG. 7 is a flow chart showing a nozzle position calculation process.

FIG. 8 is a diagram showing an example of a nozzle size variation atnozzle positions.

FIG. 9A is a diagram showing an example of a method for obtaining anozzle diameter.

FIG. 9B is a graph showing an example of a method for obtaining a nozzlediameter.

FIG. 10 is a flow chart showing a process of setting the conversioncoefficient beforehand.

FIGS. 11A and 11B are diagrams showing some processing positions of thenozzle.

FIGS. 12A and 12B are drawings showing the principle of conversionformula calculation.

FIG. 13 is a flow chart showing the conversion formula calculationprocess.

FIG. 14 is a drawing showing an example of the correction table.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A substrate processing system comprising a substrate processingapparatus to which the invention is applicable will now be brieflydescribed. In the following, a substrate may be any one of various typesof substrates such as a semiconductor substrate, a glass substrate forphoto mask, a glass substrate for liquid crystal display, a glasssubstrate for plasma display, a substrate for FED (Field EmissionDisplay), an optical disk substrate, a magnetic disk substrate and amagneto-optic disk substrate. While the following will describe as anexample a substrate processing system used primarily for processing of asemiconductor substrate with reference to drawings, the invention isapplicable to processing of various types of substrates mentioned above.

FIG. 1 is a schematic drawing showing the structure of a substrateprocessing system according to an embodiment of the invention. To bemore specific, FIG. 1 is a plan view which shows an embodiment of asubstrate processing system comprising a substrate processing apparatusto which the invention is applied in a preferable fashion. The substrateprocessing system 1 comprises substrate processing units 1A, 1B, 1C and1D, an indexer part 1E and a controller 80 (FIG. 3). The substrateprocessing units 1A, 1B, 1C and 1D are capable of executingpredetermined processing of a substrate independently of each other. Theindexer part 1E is equipped with an indexer robot (not shown) which isfor transferring the substrate to the substrate processing units 1A, 1B,1C and 1D from outside and vice versa. The controller 80 controlsoperations of the entire system. Any number of substrate processingunits may be disposed, and more than one layers each housing foursubstrate processing units which are arranged horizontally may bestacked one atop the other.

The substrate processing units 1A, 1B, 1C and 1D are identical to eachother with respect to structural elements and operations, although thelayout of the structural elements is partially different depending uponthe locations of these units within the substrate processing system 1.The following will describe the structure and operations of thesubstrate processing unit 1A but will omit describing the othersemiconductor processing units 1B, 1C and 1D in detail. As describedbelow, each of the substrate processing units 1A through 1D has afunction of a “substrate processing apparatus” which performs apredetermined process to the substrate and a function of a “displacementdetecting apparatus” of the invention using a processing nozzle as a“positioning object”.

FIG. 2 is a plan view showing the structure of one substrate processingunit. FIG. 3 is a drawing showing the cross section of FIG. 2 takenalong the arrow A-A and the structure of the controller of the substrateprocessing unit. The substrate processing unit 1A is a wet processingunit of the single wafer processing type for executing wet processing,such as cleaning and etching using a processing fluid, of a disk-shapedsubstrate W such as a semiconductor wafer. In the substrate processingunit 1A, a fan filter unit (FFU) 91 is disposed to a ceiling section ofa chamber 90. The fan filter unit 91 comprises a fan 911 and a filter912. External atmosphere which is admitted as the fan 911 operates issupplied into a processing space SP which is inside the chamber 90 viathe filter 912. The substrate processing system 1 is used as it isinstalled inside a clean room, and the processing space SP continuouslyreceives clean air all times.

A substrate holder 10 is disposed inside the processing space SP of thechamber 90. The substrate holder 10 is for rotating the substrate Wwhile maintaining the substrate W in an approximate horizontal postureso that the one surface of the substrate W is directed toward above. Thesubstrate holder 10 comprises a spin chuck 11 in which a disk-shapedspin base 111 whose outer diameter is slightly larger than the substrateW and a rotation support shaft 112 which elongates approximately alongthe vertical direction are integrated and linked with each other. Therotation support shaft 112 is linked with the rotation shaft of a chuckrotating mechanism 113 which includes a motor so that it is possible forthe spin chuck 11 to rotate about the rotation shaft (the vertical axis)when driven by a chuck driver 85 of the controller 80. The rotationsupport shaft 112 and the chuck rotating mechanism 113 are housed insidea cylindrical casing 12. The spin base 111 is integrated and linked withthe top end of the rotation support shaft 112 by a fastening componentsuch as a screw, and the spin base 111 is supported by the rotationsupport shaft 112 approximately horizontally. Hence, as the chuckrotating mechanism 113 operates, the spin base 111 rotates about thevertical axis. The controller 80 controls the chuck rotating mechanism113 via a chuck driver 85, which makes it possible to adjust therotation speed of the spin base 111.

There are a plurality of chuck pins 114 for grabbing the substrate W atthe peripheral edge which are disposed in the vicinity of the peripheraledge of the spin base 111. There may be three or more (six in thisexample) such chuck pins 114 for the purpose of securely holding thecircular substrate W. The chuck pins are disposed at equal angularintervals along the peripheral edge of the spin base 111. Each chuck pin114 is structured so as to be able to switch between the pressing statein which it presses the exterior peripheral edge surface of thesubstrate W and the released state in which it is off the exteriorperipheral edge surface of the substrate W.

Each one of the chuck pins 114 is released when the substrate W ishanded over to the spin base 111 but remains in the pressing state whenthe substrate W is rotated and subjected to predetermined processing.When in the pressing state, the chuck pins 114 can hold the substrate Wat the peripheral edge of the substrate and keep the substrate Wapproximately horizontally over a predetermined gap from the spin base111. Thus, the substrate W is supported with its top surface directedtoward above and its bottom surface directed toward below. The chuckpins 114 are not limited to above structure but may be of one of variousknown structures. The mechanism for holding substrates is not limited tochuck pins but may instead be a vacuum chuck which sucks the substrate Wat the back surface of the substrate and thereby holds the substrate.

Around the casing 12, a splash guard 20 is disposed which surrounds thesubstrate W which is held horizontally by the spin chuck 11 in such amanner that the splash guard 20 can move upward and downward along adirection of the rotation shaft of the spin chuck 11. The splash guard20 has an approximately rotation symmetric shape with respect to therotation shaft, and comprises a plurality of guards 21 (two guards inthis example), which are each disposed concentric to the spin chuck 11and receive a splashed processing fluid from the substrate W, and afluid receiver 22 which receives the processing fluid flowing down fromthe guards 21. As a guard up-down mechanism not shown disposed to thecontroller 80 makes the guards 21 ascend or descend stepwise, it ispossible to segregate and collect a processing fluid such as a chemicalsolution and a rinse solution splashed around from the rotatingsubstrate W.

Around the splash guard 20, at least one fluid supplier is disposedwhich provides the substrate W with various types of processing fluidssuch as a chemical solution which may be an etching solution, a rinsesolution, a solvent, pure water and DIW (deionized water). In thisexample, as shown in FIG. 2, there are three fluid dischargers 30, 40and 50. The fluid discharger 30 comprises a revolving shaft 31, whichcan revolve about the vertical axis when driven by an arm driver 83 ofthe controller 80, an arm 32 extending horizontally from the revolvingshaft 31, and a nozzle 33 which is attached as it is directed towardbelow to the tip end of the arm 32. As the arm driver 83 drives therevolving shaft 31, the arm 32 swings about the vertical axis, wherebythe nozzle 33 reciprocally moves between a retracted position which isoutward beyond the splash guard 20 (i.e., the position denoted by thesolid line in FIG. 3) and a position above the center of rotation of thesubstrate W (i.e., the position denoted by the dotted line in FIG. 3) asshown by the two-dot chain line in FIG. 2. The nozzle 33, while stayingabove the substrate W, discharges a predetermined processing fluidsupplied from a processing fluid supplier 84 of the controller 80 andaccordingly supplies the processing fluid to the substrate W.

Similarly, the processing fluid discharger 40 comprises a revolvingshaft 41 which is driven by the arm driver 83, an arm 42 linked withthis revolving shaft 41, and a nozzle 43 which is attached to the tipend of the arm 42 and discharges the processing fluid fed from theprocessing fluid supplier 84. The processing fluid discharger 50comprises a revolving shaft 51 which is driven by the arm driver 83, anarm 52 linked with this revolving shaft 51, and a nozzle 53 which isattached to the tip end of the arm 52 and discharges the processingfluid fed from the processing fluid supplier 84. The number of theprocessing fluid dischargers is not limited to this but may be increasedor decreased as needed.

Note that chain double-dashed lines in FIG. 2 indicate movementtrajectories of the respective nozzles 33, 43 and 53. As is understoodfrom this, each nozzle 33, 43, 53 moves along an arc on a horizontalplane from the retracted position to a peripheral edge part of thesubstrate W on a side distant from the retracted position beyond thecenter of rotation of the substrate W. The processing fluid can bedischarged from each nozzle both in a state where the nozzle is fixedlypositioned above the substrate W and in a state where the nozzle ismoving above the substrate W. In this way, various wet processes can berealized.

In a condition that the substrate W is rotating at a predeterminedrotation speed as the spin chuck 11 rotates, the processing fluiddischargers 30, 40 and 50 supply the processing fluid to the substrate Wwhile the nozzles 33, 43 and 53 become positioned above the substrate Wone after another, thereby performing wet processing of the substrate W.Different processing fluids or the same processing fluid may bedischarged at the nozzles 33, 43 and 53 in accordance with the purposeof processing. Alternatively, two or more types of processing fluids maybe discharged from one nozzle. The processing fluid supplied to thevicinity of the center of rotation of the substrate W spreads outwardlydue to centrifugal force which develops as the substrate W rotates, andeventually gets drained off toward the side from the peripheral edge ofthe substrate W. The processing fluid thus splashed by the substrate Wis then received by the guards 21 of the splash guard 20 and collectedby the fluid receiver 22.

The substrate processing apparatus 1A further comprises an illuminator71 which illuminates inside the processing space SP and a camera 72which is neighboring of the illuminator 71 and takes an image of thesurface of inside the chamber 90. The illuminator 71 uses an LED lamp asa light source for instance, and provides illumination light into insidethe interior of the processing space SP which is needed for taking animage with the camera 72. The camera 72 is disposed at a higher positionas compared with the substrate W along the vertical direction, and itsimaging direction (i.e., the direction of the optical axis of theimaging optical system) is set as a downwardly oblique direction towardthe approximate center of rotation in the surface of the substrate W soas to take an image of the top surface of the substrate W. The entiresurface of the substrate W held by the spin chuck 11 thus comes intoinside the field of view of the camera 72. In horizontally, an areabetween the two dashed lines in FIG. 2 is included in the field of viewof the camera 72.

Note that the illuminator 71 and the camera 72 may be disposed insidethe chamber 90, or they may be disposed outside the chamber 90 so as toilluminate or take an image of the substrate W via a transparent windowprovided in the chamber 90. In terms of preventing the adhesion of theprocessing liquid and exposure to a processing atmosphere, these arepreferably disposed outside the chamber 90.

Image data output from the camera 72 are fed to an image processor 86 ofthe controller 80. The image processor 86 then performs predeterminedimage processing of the image data such as a correction processing or apattern matching processing described later. As described later indetail, in this embodiment, in accordance with images taken by thecamera 72, how the nozzles 33, 43 and 53 are positioned and how thesubstrate W is held is determined. Further, the installment position ofthe camera 72 relative to the chamber 90 could get deviated from theappropriate position, which can be handled by the structure according tothis embodiment.

For these purposes, alignment marks 61 through 64 which serve asposition references are fixed at a plurality of positions which arewithin the field of view of the camera 72 and which are on an inner wallsurface 901 of the chamber 90. The positions of the alignment marks 61through 64 inside the chamber 90 have been determined in advance. Thealignment marks 61 through 64 are so arranged that as illumination lightirradiated from the illuminator 71 is reflected at the surfaces of thealignment marks 61 through 64, the reflected light impinges upon thecamera 72. The alignment marks 61 through 64 contained within an imageshot by the camera 72 are used as position references which are forassessment of the positions and the postures of the camera 72, therespective nozzles 33, 43 and 53 and the substrate W.

In addition to the above, the controller 80 of the substrate processingsystem 1 comprises a CPU 81, a memory 82 and a display 87. The CPU 81executes a processing program set in advance and accordingly controlsoperations of the respective parts. The memory 82 stores the processingprogram executed by the CPU 81, data created during processing, etc. Thedisplay 87 informs a user as needed of a progress in processing,abnormality, etc. Each one of the substrate processing units 1A through1D may have one such controller 80, or only one controller 80 may bedisposed for the substrate processing system 1 for control of allsubstrate processing units 1A through 1D. Further, the CPU 81 mayfunction as an image processor as well.

The operation of the substrate processing unit 1A having the structureabove will now be described. The other substrate processing units 1Bthrough 1D operate similarly although they will not be described.Through the indexer part 1E, the substrate processing unit 1A receivesthe substrate W which has been transported from outside and suppliesvarious types of processing fluids while rotating the substrate W,thereby executing wet processing. A number of known techniques areavailable which use various types of processing fluids for wetprocessing, and any such technique may be used.

FIG. 4 is a flow chart showing the operation of the substrate processingunit. This operation is realized as the CPU 81 executes thepredetermined processing program. The substrate W is loaded into thesubstrate processing unit 1A and is then set to the spin chuck 11, morespecifically, to the plurality of chuck pins 114 which are disposed tothe peripheral edge of the spin base 111 (Step S101). During loading ofthe substrate W, the chuck pins 114 disposed to the spin base 111 are inthe released state but switch to the pressing state after the substrateW is set at the chuck pins 114 and accordingly hold the substrate W. Inthis state, the camera 72 takes an image of inside of the chamber 90(Step S102).

FIG. 5 is a schematic drawing showing an example of an image which isobtained by imaging inside the chamber. An image I1 shot by the camera72 which is installed at such a position which looks down on thesubstrate W contains the substrate W which is mounted on the spin base111 and the respective members such as the splash guard 20 whichsurrounds the substrate W, fluid dischargers 30 and 40 and the alignmentmarks 61 through 64. The assumption is that the camera 72 is attached atan appropriate position relative to the chamber 90.

In image examples in FIG. 5 and later figures, the upper and leftcorners of the images are regarded as origins and the horizontaldirection and the vertical direction of the images are defined asX-direction and Y-direction respectively. Each position in one image maybe specified by coordinate of the X-Y image plain which is representedby the X-coordinate extending rightward from the origin and theY-coordinate extending downward from the origin.

The alignment marks 61 through 64 are arranged at dispersed positions onthe chamber inner wall 901 which are within the field of view of thecamera 72 and which are not blocked by the substrate W or the respectivemembers disposed inside the chamber 90 such as the fluid dischargers 30and 40. Specifically, the alignment marks 61 and 64 are so arranged thatthey are captured by the camera at such positions which are around thecenter of the image I1 along the perpendicular direction and which areclose to the far-left and the far-right along the horizontal direction.Meanwhile, the alignment marks 62 and 63 are arranged such that they areapart from each other horizontally close to the top edge of the imageI1. As the alignment marks 61 through 64 are dispersed in this manner,it is possible to enhance the accuracy during detection of deviation ofthe camera 72 which will be described later.

Although the alignment marks 61 through 64 may be of any desiredmaterial and may have any desired shapes, it is desirable that thecamera 72 can shoot them under illumination light from the illuminator71 in sufficient contrast for position detection. More preferably, it isdesirable that the shapes of the alignment marks can be detected at ahigh accuracy from an image which was shot. The alignment marks 61through 64 in this substrate processing unit 1A are rectangle platemembers which bear the mark which looks like “+” as shown in FIG. 5. Forinstance, plate members of stainless steel on which the mark above isengraved or painted may be used. Provision of the alignment marks whichhave these characteristics makes it possible to highly accurately detectnot only the positions of the alignment marks but rotation, the sizesand the like within the image as well.

In the event that the direction in which the illumination light impingesand the direction of the optical axis of the camera 72 generally matchwith each other as in the case of the unit 1A in which the camera 72 andthe illuminator 71 are disposed in the vicinity of each other, it ispreferable that at least one of the plate members and the marks isformed by a retroreflective material. This secures that the reflectedlight from the alignment marks impinges upon the camera 72 without fail,thereby making it possible to shoot high-contrast images of thealignment marks using large light quantity. In consequence, the accuracyfor detecting the positions of the alignment marks is further increased.

As indicated by the double chain line in FIG. 5, the nozzles 33 and 43which discharge the processing fluid are capable of moving horizontally.As the processing fluid is discharged in a condition that these nozzlesare located at predetermined positions above the substrate W, thesubstrate W is processed. The nozzle 53 (FIG. 2) not shown in FIG. 5 aswell, as a trajectory thereof is shown in broken line in FIG. 5, whenmoving toward above the substrate W, comes into the field of view of thecamera 72. Using an image shot with the camera 72, it is possible todetermine whether the positions of the nozzles during execution of theprocessing are appropriate. In this manner, it is possible to avoidinappropriate processing by any nozzle which is at an inappropriateposition and to stably process the substrate W.

However, it is possible that the camera 72 per se could be deviatedrelative to the chamber 90 because of contact with any member duringloading or unloading of the substrate W, vibration during the processingor the like for instance. It is therefore necessary to preventmisdetection of the position of any nozzle due to such deviation. Inthis embodiment, the alignment marks 61 through 64 are fixed to theinner wall surface 901 of the chamber 90 and the position of eachalignment mark 61 through 64 inside the chamber 90 remains unchanged.Thus, the position of each alignment mark 61 through 64 is preciselyknown in advance for an image imaged by the camera 72 mounted at aproper position with respect to the chamber 90.

From this, the presence or absence of a positional displacement of thecamera 72 can be determined based on whether or not the alignment marks61 through 64 are at predetermined positions in the imaged image. Aplurality of the alignment marks 61 through 64 are arranged to appear atdispersed positions in the image. Thus, the presence or absence, thesize, the direction and the like of the positional displacement of thecamera 72 can be detected from these position detection results in theimage.

Referring back to FIG. 4, the flow chart is further described. Using theimage inside the chamber 90 imaged in Step S102, the positions of thealignment marks 61 through 64 in the image are detected based on theabove principle (Step S103). A positional displacement amount of thecamera 72 is evaluated based on that detection result. If the positionaldisplacement amount is within an allowable range determined in advance(YES in Step S104), processings in and after Step S105 are performed. Onthe other hand, if the positional displacement amount is beyond theallowable range (NO in Step S104), the occurrence of a cameraabnormality is notified to the user, for example, by displaying apredetermined error message on the display 87 (Step S121) and theprocess is finished.

If the camera 72 is largely shifted for a certain cause, any one of thealignment marks may be deviated from an imaging visual field. In such acase, the position of this alignment mark cannot be detected. It isclear that this state causes a problem in the subsequent detection and,hence, this case may be also regarded as a camera abnormality.

In this substrate processing unit 1A, a positional displacement of thecamera 72 is detected as described above. If there is a small positionaldisplacement as a result of the detection, the process is continued onthe assumption that the positional displacement is corrected by an imageprocessing. On the other hand, if there is a large positionaldisplacement unavoidably resulting in a reduction of detection accuracyeven if a correction is made, the process is stopped. In this way, acertain positional displacement of the camera 72 is allowed and theprocess is continued. It possibly causes reductions in the throughput ofthe process and an operating rate of the system that the entire processis stopped due to the positional displacement of the camera 72 notdirectly contributing to the substrate processing. In the above way, aprobability of causing such a situation can be reduced. On the otherhand, by stopping the process, when there is a large positionaldisplacement, it is prevented that an improper process is performed onthe substrate.

If the obtained positional displacement amount of the camera 72 iswithin the allowable range, information indicating the positionaldisplacement amount at that time is stored in the memory 82 (Step S105).This information is used as correction information in detecting theposition of the nozzle later. Note that the information stored in thememory 82 may be position information of each alignment mark 61 through64 or may be information on the positional displacement amount of thecamera 72 calculated from those pieces of information. Any piece ofinformation reflects the position information of each alignment markdetected from the image and indicates the positional displacement amountof the camera 72.

Subsequently, whether or not the substrate W is properly held by thespin chuck 11 is determined (Step S106). If the substrate W is placedwhile being inclined with respect to the spin base 111 or deviated fromthe rotation center, a problem that the substrate W falls or abnormallyvibrates during the rotation of the spin chuck 11 possibly occurs. Toavoid these, the holding state of the substrate W is determined beforethe spin chuck 11 is rotated. The holding state can be determined, forexample, based on the posture of the substrate W detected from theimage.

A known pattern matching technique can be used for the detection of thesubstrate W in the image. Besides, a known ellipse detection algorithmcan be used as a method capable of detection in a shorter time.Specifically, ellipses of a size corresponding to a diameter of thesubstrate W are searched by an appropriate ellipse detection algorithm,using a coordinate range in an area having a high probability of beingtaken up by the substrate W in the image as a search area. As a result,center coordinates and sizes in X and Y directions of the ellipsematching the condition are obtained.

If these numerical values substantially match numerical values in anideal holding state, it can be determined that the substrate W isproperly held. On the other hand, if the numerical values largelydeviate, it can be determined that the substrate W is improperly held.

Note that the posture of the substrate W detected from the image is theaddition of the posture of the substrate W in the processing space SPand the influence of the positional displacement of the camera 72described above. Thus, the posture of the substrate W obtained by thesearch is compared with the ideal state after the influence by thepositional displacement of the camera 72 is subtracted based on theposition information of the alignment marks obtained earlier, and theholding state is determined from that result.

Referring back to FIG. 4 again, the flow chart is further described. Ifit is determined that the substrate W is improperly held by the spinchuck 11 (NO in Step S106), the occurrence of a chuck abnormality isnotified to the user, for example, by displaying a predetermined errormessage on the display 87 (Step S122) and the process is finished. Inthis way, the fall and abnormal vibration of the substrate W due to therotation of the spin chuck 11 in the improper holding state can beavoided.

If the holding state is proper (YES in Step S106), the spin chuck 11 isrotated at a predetermined rotation speed for the substrate processing(Step S107). Subsequently, the arm driver 83 is activated to positionany one of the plurality of nozzles at a predetermined processingposition facing the substrate W (Step S108). Although the process usingthe nozzle 43 is described below, a similar operation is performed alsoin the case of using the other nozzles 33, 53. Further, the plurality ofnozzles may be simultaneously used for the process. When the nozzle 43is positioned at the processing position, the camera 72 images theinterior of the chamber 90 (Step S109) and the position of the nozzle 43is determined based on that image (Steps S110, S111).

FIG. 6 is a drawing showing an example of an image obtained by imagingthe nozzle. More specifically, an example of an image 12 obtained byimaging the interior of the chamber 90 with the nozzle 43 positioned atthe processing position above the substrate W is shown in FIG. 6. Thecontroller 80 can learn the processing position of the nozzle 43 by aprior teaching operation. Here, it is assumed that a position above therotation center C of the substrate W is set as the processing positionof the nozzle 43.

A reference matching pattern and box information are obtained from animage imaged in advance in a state where there is no positionaldisplacement of the camera 72 or the positional displacement is properlycorrected and the nozzle 43 is correctly positioned at the processingposition by the prior teaching operation. Specifically, an image patternof an area Ba taken up by the nozzle 43 in the image is obtained as thereference matching pattern and coordinate information of the area Ba isobtained as the box information used for the detection of the nozzleposition when the process is performed on the substrate. These pieces ofinformation are stored in the memory 82 in advance. Every time theprocess is performed on the substrate, the position of the nozzle 43 isdetected from the image 12 imaged in Step S109 and the positionaldisplacement amount of the nozzle 43 is calculated by comparing thedetected position with the box information (Step S110). Based on thatresult, whether or not the position of the nozzle 43 is proper isdetermined (Step S111).

FIG. 7 is a flow chart showing a nozzle position calculation process.This flow chart more specifically explains the processing contents ofStep S110 of FIG. 4. In this process, the nozzle 43 is first detectedfrom the image 12 using the pattern matching technique (Step S201). Thefollowing two methods are, for example, considered as a method fordetecting the nozzle 43 from the image 12 by the pattern matchingtechnique. The first method is a method for searching the area Ba havingimage contents matching the reference matching pattern stored in thememory 82 in the image 12. Further, the second method is a method forcomparing image contents of the area Ba specified by the box informationstored in the memory 82 out of the image 12 with those of the referencematching pattern and evaluating a matching score between the both.Either one of the methods may be used and a method other than those mayalso be used.

When the area Ba corresponding to the nozzle 43 is detected in the image12, the position coordinates thereof are obtained and stored in thememory 82 (Step S202). Typical coordinates indicating the position ofthe area Ba such as the coordinates of a left-upper corner of the areaBa or those of a centroid of the area Ba can be used as the positioncoordinates of the nozzle 43. Note that if there is a positionaldisplacement of the camera 72, the coordinates are appropriatelycorrected to compensate for this positional displacement in processingsof Steps S201 and S202.

Subsequently, the position of the nozzle 43 obtained in the image 12 isconverted into a displacement amount of the nozzle 43 from the referenceposition in the actual space inside the chamber 90 by a conversionmethod to be described later (Step S203). A particular position insidethe chamber 90 is specified as the reference position in advance. Forexample, the processing position can be used as the reference position.However, if a positional relationship with the processing position as atarget position of the nozzle 43 is clear, the reference position may bedifferent from the processing position. On the other hand, necessaryinformation is the positional displacement amount of the nozzle 43 fromthe designated processing position in the actual space. Therefore, thepositional displacement amount from the processing position of thenozzle 43 is calculated based on the positional relationship of thereference position and the processing position known in advance if thesepositions are different (Step S204).

As just described, in this embodiment, how much the positioned nozzle isdeviated from the reference position is evaluated by obtaining thedisplacement amount of the nozzle in the image 12 and converting theobtained displacement amount into the displacement amount in the actualspace. The positional displacement amount of the nozzle is, for example,represented by a pixel number in the image 12, whereas the positionaldisplacement amount in the actual space has a length dimension. Thus, inprinciple, the displacement amount in the actual space can be calculatedby multiplying the displacement amount (pixel number) in the image by alength per pixel if a correspondence relationship between one pixel inthe image and a length in the actual space is known.

However, the displacement amount per pixel is not uniform in the imageand differs depending on a distance between a camera and an object to beimaged. Particularly, since distances to the nozzles 33, 43 and 53 asobjects to be imaged are relatively short and these nozzles move in wideranges, an angle of view of the camera 72 need to be wide to keep thesewithin an imaging visual field. Thus, the displacement amount per pixellargely varies depending on the distances of the nozzles 33, 43 and 53from the camera 72.

FIG. 8 is a diagram showing an example of a nozzle size variation atnozzle positions. Note that the configuration not directly related toexplanation is not shown in FIG. 8 to make the figure easily viewable.Among when the nozzle 43 is at a position P1 above the peripheral edgepart of the substrate W on a side near the retracted position, when thenozzle 43 is at a processing position P2 above the center of rotation Cof the substrate W and when the nozzle 43 is at a position P3 above theperipheral edge part of the substrate W on the side distant from theretracted position beyond the processing position, the apparent size ofthe nozzle 43 in an image 13 largely changes due to differences indistance from the camera 72. Thus, a diameter Dn of the nozzle 43grasped from the image differs depending on the nozzle position.Specifically, when a width of an area taken up by the nozzle 43 in theimage 13 is expressed by a pixel number, this pixel number differsdepending on the nozzle position. Of course, the size of the nozzledoesn't change in the actual space.

Similarly to this, the displacement amount of the nozzle appearing inthe image differs depending on the nozzle position. Specifically, evenif the displacement amount of the nozzle 43 in the actual space is thesame, a large displacement appears in the image at a position where thenozzle 43 appears to be relatively large in the image and, conversely, adisplacement appearing in the image is also small at a position wherethe nozzle 43 appears to be relatively small in the image. Converselyspeaking, the displacement amount in the actual space equivalent to adisplacement of one pixel in the image is larger when the nozzle 43 isdistant from the camera 72 and appears to be relatively small in theimage than when the nozzle 43 is close to the camera 72 and appears tobe relatively large in the image.

If the displacement amount per pixel is changed in accordance with achange of the size of the nozzle 43 or the like appearing in the imagein converting the displacement amount in the image into the displacementamount in the actual space, the problem as described above can be dealtwith and the displacement amount in the actual space can be accuratelyobtained. Specifically, the coefficient by which the displacement amountexpressed by the pixel number in the image is multiplied may be setaccording to the size of the nozzle in the image. The coefficient isequivalent to the displacement amount in the actual space correspondingto the displacement amount of one pixel in the image. For this purpose,the size of the nozzle appearing in the imaged image is obtained. Inthis embodiment, a diameter of the cylindrical nozzle 43 is obtained.

FIGS. 9A and 9B are a diagram and a graph showing an example of a methodfor obtaining a nozzle diameter. As shown in FIG. 9A, a horizontalstraight line La is set in an area Ba corresponding to the nozzle 43detected in the image 12 by pattern matching. The straight line La isset to cross the nozzle 43 included in the area Ba. Then, a luminancevalue of each pixel located on this straight line La is obtained. Asshown in FIG. 9B, by detecting notable luminance values appearing inparts corresponding to both side end surfaces of the nozzle 43, adistance between the both side end surfaces of the nozzle, i.e. a nozzlediameter is obtained. For example, an appropriate threshold value Lth isset for the luminance values, positions where the luminance value islarger than the threshold value Lth are regarded as edge positions andthe nozzle diameter can be expressed by the number of pixels includedbetween two edge positions.

The nozzle diameter at this time can be expressed by the number of thepixels taking up a range corresponding to a surface (side surface) ofthe nozzle 43 on the straight line La. Since the diameter of the nozzle43 is known in advance, a length in the actual space equivalent to onepixel in the image can be obtained by dividing the value of the diameterby the number of pixels between the edges. The length per pixel obtainedin this way serves as a conversion coefficient in converting thedisplacement amount in the image expressed by the pixel number into thedisplacement amount in the actual space.

If a nozzle tip part has a cylindrical shape, the nozzle size can bespecified by the nozzle diameter without depending on the position ofthe nozzle tip part. In a configuration in which the nozzle is moved andpositioned by the swingable arm as in this embodiment, the orientationof the nozzle with respect to the camera 72 varies depending on theposition of the nozzle. If the nozzle tip part has a cylindrical shape,there is no influence caused by orientation differences.

Note that the shape of the nozzle is not limited to the cylindricalshape. Also with a nozzle having an arbitrary shape, the size detectionof the nozzle can be facilitated, for example, by providing a markerhaving dimensions determined in advance, scales at regular intervals orthe like if necessary.

Other methods for obtaining the nozzle size include a method usinginformation obtained by pattern matching. Specifically, in patternmatching, the area Ba corresponding to a reference matching patternprepared in advance is detected from the image 12 to be processed. Atthis time, a higher matching score may be obtained by enlarging orreducing the reference matching pattern. This means that an object to beimaged (nozzle in this case) corresponding to the reference matchingpattern appears in the image 12 in a size larger or smaller than animage from which the reference matching pattern was obtained.

In other words, an enlargement rate or reduction rate of the referencematching pattern applied in pattern matching for the image 12 representsa relative nozzle size on the basis of the nozzle size indicated by thereference matching pattern. Thus, if only the nozzle size in thereference matching pattern is obtained in advance, the nozzle size in anarbitrary image can be obtained by multiplying the obtained value by theenlargement rate or reduction rate of the reference matching patternapplied in pattern matching. Since information for estimating the nozzlesize is obtained when the nozzle position is specified by patternmatching in this method, an operation for calculating the nozzle sizeanew is not necessary.

Note that, in terms of setting the conversion coefficient of thedisplacement amount from the image into the actual space, it issufficient to obtain the length in the actual space equivalent to onepixel of the image. Thus, the conversion coefficient corresponding to anarbitrary nozzle position can be directly obtained even withoutobtaining the nozzle size by multiplying the conversion coefficient atthe position where the reference matching pattern was obtained by theabove enlargement rate or reduction rate.

As just described, in this embodiment, the conversion coefficient forconverting the displacement amount in the image expressed by the pixelnumber into the displacement amount in the actual space is changed andset according to the size of the nozzle 43 or the like in the image. Bydoing so, the positional displacement amount of the nozzle 43 or thelike from the processing position in the actual space can be accuratelyobtained in spite of a change of the displacement amount per pixelcaused due to a difference in distance from the camera 72.

Referring back to FIG. 4, the flow chart is further described. It isdetermined whether or not the positional displacement amount of thenozzle 43 from the processing position obtained as described above iswithin an allowable range determined in advance (Step S111). If withinthe allowable range (YES in Step S111), the wet process is performed bysupplying the predetermined processing liquid from the nozzle 43 to thesubstrate W (Step S112). If the positional displacement amount of thenozzle 43 is beyond the allowable range (NO in Step S111), theoccurrence of a nozzle abnormality is notified to the user, for example,by displaying a predetermined error message on the display 87 (StepS123) and the process is finished. In this way, it can be avoided thatthe processing liquid is supplied from the nozzle 43 at an improperposition to lead to a failure in processing result. Further, since it isguaranteed that the process is performed by the nozzle 43 positioned ata proper position, a good processing result can be stably obtained.

Next, a specific method for reflecting the size of the nozzle withrespect to the image on the conversion coefficient in converting thedisplacement amount in the image into the displacement amount in theactual space is described. Following two methods are, roughly, thoughtas this method. The first method is a method for obtaining theconversion coefficient of the displacement amount from the image intothe actual space for each type of the nozzle and each processingposition in advance. The second method is a method for detecting thenozzle size in real time and setting the conversion coefficient duringthe execution of the nozzle position calculation process shown in FIG.7.

The first method is more specifically described. The trajectory of eachnozzle 33, 43, 53 moving by a swinging movement of the arm 32, 42, 52 isdetermined in advance. One or more positions on the trajectory are setas the processing positions and any one of the nozzles is positioned atone processing position when the wet process for the substrate W isperformed. At this time, for the purpose of confirming whether or notthe nozzle is properly positioned at the processing position, Step S110of FIG. 4, i.e. the nozzle position calculation process shown in FIG. 7is performed.

At the processing position and in a range near the processing position,the displacement amount in the actual space equivalent to one pixel ofthe image can be practically regarded to be substantially constant.Thus, the conversion coefficient near one processing position can beobtained beforehand for each processing position of each nozzle. Bydoing so, the positional displacement of the nozzle can be determined byapplying the conversion coefficient set in advance in actuallyprocessing the substrate W, and the processing can be simplified.

FIG. 10 is a flow chart showing a process of setting the conversioncoefficient beforehand. Although the process for the nozzle 43 isdescribed here, a similar process may be performed also for the othernozzles 33, 53. Firstly, the arm driver 83 rotates the arm 42 by apredetermined amount, whereby the nozzle 43 is positioned at oneprocessing position (Step S301). In this state, the inside of thechamber 90 is imaged by the camera 72 (Step S302), and the nozzle 43 isdetected from an image by the image processor 86 (Step S303). Theposition coordinates and size (diameter) of the nozzle 43 are calculatedand stored in the memory 82 (Step S304). Specific methods for theposition detection and size detection of the nozzle are described above.Imaging and the detection of the position and size of the nozzle areperformed while the processing positions are successively switched untilthe above process is finished for all the processing positions (StepS305).

Since the diameter of the nozzle 43 is known, the conversion coefficientfrom the image into the actual space near the processing position can beobtained by dividing an actual diameter by the nozzle diameter detectedin the image corresponding to one processing position. By performingthis for each processing position (Step S306), the conversioncoefficients corresponding to all the processing positions are obtained.The obtained conversion coefficients and the processing positions arerelated and stored, for example, in a table format in the memory 82(Step S307).

When the displacement amount of the nozzle 43 is obtained in the actualprocess shown in FIGS. 4 and 7, the conversion coefficient correspondingto the processing position is read from the memory 82. The displacementamount of the nozzle 43 in the actual space is calculated by multiplyinga distance between the processing position and the detected nozzleposition in the image by the conversion coefficient. Since arelationship between the conversion coefficient determined according tothe nozzle size in the image and the processing position is determinedin advance, the nozzle size needs not be calculated in calculating thedisplacement amount of the nozzle.

The calculation process of the conversion coefficient described above isperformed before the substrate W is processed if necessary such as whena component inside the chamber 90 is exchanged, when a new component ismounted, during a new teaching operation and during a regularmaintenance operation and the like besides before the shipment of theapparatus.

Next, the second method for reflecting the size of the nozzle in theimage on the conversion coefficient is described. In this method, theposition and size of the nozzle 43 are detected from the image 12 imagedin the process shown in FIG. 4, and the conversion coefficient isdynamically set based on that result. The nozzle size is obtained in theaforementioned way. For example, the method shown in FIG. 9 and themethod utilizing the enlargement rate or reduction rate of the referencematching pattern in pattern matching can be applied.

Only the conversion coefficient corresponding to the nozzle position(e.g. processing position above the center of rotation C of thesubstrate W) when the reference matching pattern was obtained is set inadvance as a reference conversion coefficient. Then, by scaling thereference conversion coefficient according to the nozzle size detectedin an arbitrary image, the conversion coefficient corresponding to thenozzle position in this image is determined. For example, the conversioncoefficient of the displacement amount from the image into the actualspace can be properly obtained according to the nozzle size bymultiplying the reference conversion coefficient by an inverse of theenlargement rate or reduction rate of the reference matching patternapplied in pattern matching.

According to this method, the conversion coefficient needs not beobtained at each position beforehand. Thus, even if a processingposition is, for example, added ex post facto, the positionaldisplacement amount of the nozzle with respect to this processingposition can be properly evaluated without any particular preparation.

Note that a length obtained by multiplying the distance between thenozzle position and the processing position in the image by theconversion coefficient determined according to the nozzle size isobtained as the positional displacement amount of the nozzle in theactual space here. It is then determined whether or not the obtainedpositional displacement amount is within the allowable range. However,for the purpose of determining whether or not the positionaldisplacement amount of the nozzle in the actual space is within theallowable range, the comparison of a value obtained by dividing theallowable positional displacement amount by the conversion coefficientand the positional displacement amount detected in the image istechnically equivalent.

Next, another method for calculating the positional displacement amountfrom the processing position in the actual space based on the positionof the nozzle detected in the image is described. In the above methods,the displacement amount in the actual space equivalent to one pixel inthe image is expressed by the conversion coefficient set according tothe size of the nozzle detected in the image. Then, the displacementamount of the nozzle in the actual space is estimated by multiplying thepositional displacement amount from the processing position detected inthe image by the conversion coefficient.

On the other hand, in the method described next, a correspondencerelationship of the nozzle position in the image and the position in theactual space is obtained in advance for each position on an arcuatenozzle movement path. The nozzle position detected in the image isconverted into a nozzle position in the actual space based on thecorrespondence relationship, whereby the positional displacement amountfrom the processing position is obtained. How to obtain a conversionformula for this is described below. Note that for the purpose ofdetermining whether or not the nozzle is properly positioned, thecoordinate position of the nozzle 43 in the actual space needs not bespecified and it is sufficient to accurately obtain the positionaldisplacement amount from the reference position.

Although how to obtain a conversion formula corresponding to one nozzle43 is described here, a similar process is possible also for the othernozzles 33, 53. Further, the configuration of the apparatus and basicoperations of each unit are not different at all from those of theembodiment described above except the conversion method for obtainingthe displacement amount in the actual space from the nozzle positiondetected in the image.

As shown in FIG. 2 and FIG. 5, the arm 42 rotates about the rotary shaft41, whereby the nozzle 43 moves along an arc including the processingposition above the rotation center of the substrate W in the horizontaldirection. On the other hand, the image 12 is imaged by the camera 72arranged to look down upon a movement path of the nozzle 43 obliquelyfrom an upper side. Thus, a trajectory of the nozzle 43 in the images 12when the nozzle 43 moves along that movement path is complicated.Further, particularly near an end part of the image, the image may bedistorted due to lens characteristics of the camera 72. By these causes,a moving direction and a movement amount of the image of the nozzle 43generally have a nonlinear relationship between the movement in theactual space and the movement in the images 12.

FIGS. 11A and 11B are diagrams showing some processing positions of thenozzle. More specifically, FIG. 11A is a diagram showing a relationshipof a movement path of the nozzle and a reference position at anintermediate position of the movement path and FIG. 11B is a top view.As described above, the nozzle 43 horizontally moves while drawing anarcuate trajectory, and at least one reference position is set on thatmovement path. Here is described a case where the position P1 where thenozzle 43 is located right above the peripheral edge part of thesubstrate W on the side near the retracted position and the position P2where the nozzle 43 is located right above the center of rotation C ofthe substrate W, which are both nozzle positions (processing positions)during the wet process, are the reference positions as shown in FIGS.11A and 11B.

Note that the number and arrangement of the set reference positions arearbitrary. As described later, in this embodiment, the conversionformula is so determined that a relationship between the nozzle positionin the image 12 and the nozzle position in the actual space is expressedwith a certain accuracy near the set reference positions. Since therelationship of the nozzle position in the image 12 and the actual spaceis generally complicated as described above, a conversion formulaaccurately expressing the relationship of the both in the entiremovement path is very complicated and unrealistic. On the other hand,the conversion formula is drastically simplified if a condition ofguaranteeing accuracy only in ranges near the reference positions isgiven.

The conversion formula assuming such a condition naturally has loweraccuracy with distance from the reference position. From this, it isdesirable to set the reference position at or near the position of thenozzle (e.g. processing position) used in the actual process. If manyreference positions are arranged in the movement path, it is possible toensure the accuracy of position detection in a wider range. The numberand arrangement of the set reference positions can be determined fromthese perspectives.

A predetermined range including the reference position P1 out of amovable range of the nozzle 43 along an arc is virtually defined as aneighborhood range R1 of the reference position P1. Further, apredetermined range including the reference position P2 out of themovable range is virtually defined as a neighborhood range R2 of thereference position P2. Although the neighborhood ranges R1, R2 are soset that the reference positions P1, P2 are centers thereof here, thereference positions may not be the centers of the neighborhood ranges.Further, the reference positions may be located at positions slightlydeviated from the neighborhood ranges.

The spreads of the neighborhood ranges R1, R2 can be appropriately setaccording to ranges necessitating good position detection accuracy. Forexample, if the reference position is the processing position, theneighborhood range is preferably set to include at least the entireallowable range of the positional displacement of the nozzle 43positioned at this processing position with the processing position as acenter. Unless the reference position is the processing position, theneighborhood range can be arbitrarily set. Further, the size of theneighborhood range can be quantitatively expressed, for example, by anyone of a length of the arc representing the movement path of the nozzle43, a magnitude of an arc angle of the arc and a linear distance betweenopposite ends of the neighborhood range. In this embodiment in which themovement of the nozzle 43 is constrained to the one on the arc, methodsfor expressing the size of the neighborhood range are technicallyequivalent. The conversion formula from the position in the image 12into the displacement amount in the actual space is so determined thatthe position of the nozzle 43 is accurately expressed in theneighborhood ranges R1, R2 set in this way.

FIGS. 12A and 12B are drawings showing the principle of conversionformula calculation. As shown by black dots in FIG. 12A, a plurality ofimaging positions are provided in each of the neighborhood ranges R1, R2on the movement path of the nozzle 43. In this embodiment, imaging isperformed every time while the position of the nozzle 43 is changed in amulti-step manner. Then, a correlation between the position of thenozzle 43 detected in the obtained image and the position of the nozzle43 in the actual space when this image was imaged is obtained. The setposition of the nozzle 43 in the actual space when this imaging isperformed is the imaging position mentioned here.

In this example, the reference position P1 is one of the imagingpositions and two imaging positions are set at each of opposite sides ofthe reference position P1 to be appropriately distributed in theneighborhood range R1. For example, the plurality of imaging positionscan be set at equal angular intervals with respect to the rotationcenter of the arm 42, i.e. at equal intervals along the movement path ofthe nozzle 43. The number of the set imaging positions is arbitrary andthe imaging positions need not always include the reference position. Byincreasing the number of samples by increasing the imaging positions,the accuracy of the conversion formula can be enhanced. For example, apositional displacement allowance of the nozzle is about (±2 mm) withrespect to the determined processing position, an interval between theimaging positions can be set at about 0.5 mm.

When imaging is performed while the nozzle 43 is positioned at theplurality of imaging positions different from each other in this way,the position of the nozzle 43 successively changes along the movementpath thereof in an obtained image 14 as shown by black dots in an upperpart of FIG. 12B. If an X-coordinate of the nozzle position in the image14 and a displacement amount of the nozzle 43 in the actual space areplotted, a nonlinear relationship generally appears between the both asshown in a lower part of FIG. 12B. Specifically, each point on a graphis connected by an appropriate curve. Note that the displacement amounttaken on a vertical axis is expressed with each of the referencepositions P1, P2 set as a starting point of displacement, the equallyset interval between the imaging positions on an arc as a path of thenozzle 43 in the actual space set as 1 unit and a direction extendingfrom a retracted position lateral to the substrate W toward thesubstrate center C (rightward direction in FIG. 12A) set as a“+direction”.

Since the movement path of the nozzle 43 in the actual space isconstrained to the one on the arc, the position of the nozzle 43 in theimage 14 can be uniquely specified only by either one of theX-coordinate and the Y-coordinate. Although the position in the image 14is expressed by an X-coordinate value here, it may be expressed by aY-coordinate value. For example, as the trajectory is shown in brokenline in FIG. 5, the nozzle 53 mainly largely moves in the Y direction inthe image, whereas a movement in the X direction is small. In such acase, it is appropriate to express the position of the nozzle by aY-coordinate value. Note that, depending on the movement of the nozzlein the image, it may not be possible to uniquely express the position ofthe nozzle by one coordinate in this way. In such a case, the positionof the nozzle 43 needs to be naturally expressed by a combination of anX-coordinate value and a Y-coordinate value.

Such a curve representing a correlative relationship between thedisplacement amount of the nozzle 43 in the actual space and theX-coordinate in the image is expressed by an approximation formula. Bydoing so, the magnitudes of the displacements of the nozzle 43 from thereference positions P1, P2 in the actual space can be obtained bysubstituting an X-coordinate value of the nozzle position detected in animage obtained by imaging the nozzle 43 into that approximation formula.Thus, this approximation formula becomes a conversion formula forobtaining the nozzle displacement amount in the actual space from thenozzle position in the image. In the case of expressing the nozzleposition in the image by a combination of an X-coordinate value and aY-coordinate value, the approximation formula also uses the X-coordinatevalue and the Y-coordinate value as parameters, but a basic concept isthe same.

Specific contents of a conversion formula calculation process based onthe above principle are described below. This process is realized by theCPU 81 executing a processing program determined in advance andperformed for one reference position of one nozzle. In other words, if aplurality of reference positions are set for one nozzle, the conversionformula calculation process is performed for each reference position.Further, if there are a plurality of nozzles for which the referencepositions are set, a similar process is performed for each nozzle.

FIG. 13 is a flow chart showing the conversion formula calculationprocess. First, the arm driver 83 rotates the arm 42 by a predeterminedamount, whereby the nozzle 43 is positioned at one of the imagingpositions (Step S401). In this state, the interior of the chamber 90 isimaged by the camera 72 (Step S402), the nozzle 43 is detected from animage by the image processor 86 (Step S403) and the position coordinatesof the nozzle 43 are stored in the memory 82 (Step S404). Until theabove process is finished for all the imaging positions (Step S405),imaging and nozzle position detection are performed while the imagingpositions are successively switched.

As the imaging position changes, the position coordinates (X- andY-coordinate values) of the nozzle 43 in the image successively change.Out of these, a coordinate axis having a larger change amount(difference between a maximum coordinate value and a minimum coordinatevalue) as a whole is selected (Step S406). By doing so, good accuracycan be ensured for the conversion formula by extending a dynamic rangeof position data.

A formula approximately expressing a correlation between the coordinatevalue of the nozzle position in the image and the displacement amount ofthe nozzle in the actual space on the selected coordinate axis isobtained as an appropriate polynomial (Step S407). The obtainedpolynomial is stored in the memory 82 as the conversion formula for thisnozzle and this reference position (Step S408). If there are a pluralityof reference positions or a plurality of nozzles, the above process isperformed for each combination of these and those results arecomprehensively stored as a correction table to be described later inthe memory 82.

Since the relationship between the position coordinate of the nozzle inthe image and the displacement amount of the nozzle in the actual spaceis generally nonlinear as described above, the conversion formula ispreferably a polynomial having two or more degrees. As the number ofdegrees of the formula increases, the relationship of the both can bemore accurately approximated. According to the knowledge of theinventors of this application, it is known to obtain practicallysufficient accuracy by a polynomial having five to six degrees. Anapproximation polynomial can be obtained, for example, by using a knownapproximation calculation method such as a least squares method.

FIG. 14 is a drawing showing an example of the correction table. Here, acase where there are three nozzles specified by nozzle numbers 1, 2 and3 and there are three reference positions specified by reference signsA, B and C for each nozzle is illustrated as an example here. However,these numbers are arbitrary. Further, the number of the referencepositions may be different for each nozzle. Furthermore, besides data onthe nozzles, data on other objects configured to be movable in thechamber 90 may also be included.

Conversion formulas F1 a(X), F1 b(X) and F1 c(X) are respectivelyprepared for the positions A, B and C of the nozzle denoted by thenozzle number 1. These are expressed as functions of the X-coordinatevalue of the nozzle in the image. On the other hand, conversion formulasF2 a(Y), F2 b(Y) and F2 c(Y) are respectively prepared for the positionsA, B and C of the nozzle denoted by the nozzle number 2. These areexpressed as functions of the Y-coordinate value of the nozzle in theimage. Further, conversion formulas F3 a(X, Y), F3 b(X, Y) and F3 c(X,Y) are respectively prepared for the positions A, B and C of the nozzledenoted by the nozzle number 3. These are expressed as functions havingtwo variables, i.e. the X-coordinate value and the Y-coordinate value ofthe nozzle in the image. As just described, the conversion formulasobtained for each nozzle and each reference position are compiled intothe correction table and stored in the memory 82.

In the nozzle position calculation process shown in FIG. 7, theconversion formula for conversion from the nozzle position detected inthe image into the displacement amount in the actual space is used inStep S203. The conversion formula is effective only near the referenceposition and differs depending on a moving direction of the nozzle.Thus, a suitable conversion formula needs to be applied for each nozzleand each reference position. In Step S203, the correction table shown inFIG. 14 is referred to and the conversion formula corresponding to thecurrently focused nozzle and processing position is selected and usedfor the process. In this way, whether or not the nozzle position isproper can be precisely determined for each nozzle and each processingposition.

The conversion formula calculation process described above is alsoperformed before the substrate W is processed if necessary such as whena component inside the chamber 90 is exchanged, when a new component ismounted, during a new teaching operation and during a regularmaintenance operation and the like beside before the shipment of theapparatus. Note that, in the case of changing a process recipe forsubstrates, the processing position, i.e. the position of the nozzlepositioned when the substrate W is processed may be possibly changedaccording to this recipe change. At this time, unless the newly setprocessing position is in a range covered by the above conversionformula, a new conversion formula needs to be obtained for the vicinityof this processing position. If the conversion formulae are obtained fora plurality of reference positions in advance, a change of the processrecipe can be easily dealt with.

As described above, in this embodiment, the nozzle position detected inthe image obtained by imaging the inside of the chamber 90 can beevaluated by being converted into the nozzle displacement amount in theactual space inside the chamber 90. This conversion is not performed bya uniform operation, but the content of the operation is dynamicallychanged according to the nozzle position.

In the first conversion method, the displacement amount in the actualspace is obtained by multiplying the nozzle displacement amount in theimage by the conversion coefficient set according to the size of thenozzle taking up in the image. On the other hand, in the secondconversion method, the conversion formula indicating the correspondencerelationship between the position on the movement path of the nozzle andthe position in the actual space is prepared in advance and thedisplacement amount in the actual space is derived from the nozzleposition coordinates detected in the image using this conversionformula.

By adopting such a configuration, how much the nozzle is deviated fromthe proper processing position in the actual space can be accuratelyevaluated in this embodiment. Thus, in the substrate processing system 1of this embodiment, a good processing result can be obtained bypreventing a processing abnormality caused by the discharge of theprocessing liquid in a state where the nozzle is at an improperposition.

The two conversion methods described above merely differ in the contentof the operation and the necessary preparation process therefor, butapparatus configurations required for the implementation of the methodsare not different at all. Thus, the both conversion methods can beimplemented for the process in one substrate processing apparatus 1. Inthis case, how to use the two conversion methods is arbitrary.

The first conversion method for reflecting the size of the nozzle in theimage on the conversion coefficient is particularly preferable when thesize of the nozzle taking up in the image largely varies depending onthe position of the nozzle. On the other hand, the second conversionmethod with which the conversion formulae between the position of thenozzle in the image and the displacement amount in the actual space areobtained in advance is preferable when the size of the nozzle in theimage does not change very much depending on the nozzle position. Fromthese, it is, for example, possible to use the first conversion methodfor such a nozzle that a distance thereof to the camera 72 largelychanges during a movement along the movement path and use the secondconversion method for such a nozzle that a change of a distance thereofto the camera 72 is small during a movement. Further, it is, forexample, also possible to compare the two conversion methods for eachnozzle beforehand and use the one having higher accuracy.

As described above, in this embodiment, each substrate processing unit1A to 1D constituting the substrate processing system corresponds to a“displacement detecting apparatus” and a “substrate processingapparatus” of the invention. The nozzle 33, 43, 53 is a “positioningobject” and an “imaging object” of the invention and has a function as a“nozzle” of the invention. Further, in the above embodiment, the arm 32,42, 52 and the arm driver 83 function as a “mover” of the invention andthe camera 72 functions as an “imager” of the invention. Further, theCPU 81 and the image processor 86 function as a “displacement detector”of the invention and the CPU 81 also functions as a “determiner” of theinvention. Further, the memory 82 functions as a “storage” of theinvention. Further, in the above embodiment, the spin chuck 11 functionsas a “holder” of the invention. Further, the substrate W corresponds toa “work” of the invention.

Further, in the above embodiment, the conversion coefficient used in theprocess of FIG. 7 corresponds to a “coefficient” of the invention.Further, the reference matching pattern used in pattern matchingcorresponds to a “reference image” of the invention.

Note that the invention is not limited to the embodiment described aboveand various changes other than those described above can be made withoutdeparting from the gist of the invention. For example, in the firstconversion method of the above embodiment, the conversion coefficientsare set only for several processing positions determined in advance foreach nozzle. However, needless to say, the conversion coefficient may beset for an arbitrary position on the movement path instead of this. Inthis case, a method may be such that conversion coefficients arecalculated by performing imaging at many nozzle positions in advance orconversion coefficients obtained for discretely set processing positionsare interpolated.

Further, although the second conversion method of the above embodimentis, for example, expressed as a conversion formula associating thenozzle position in the image and the displacement amount of the nozzlefrom the reference position in the actual space, the nozzle position inthe image and the nozzle position in the actual space may be associated.In this case, the displacement amount of the nozzle can be calculatedfrom the coordinates of the nozzle position and the reference positionin the actual space obtained by conversion. Further, besides expressionas a mathematical formula or function, conversion information can beexpressed, for example, as a look-up table in which position coordinatesin the image and a position in the actual space are associatedone-to-one. Further, the conversion formula may be approximated by abroken line.

Further, since the invention is applied to detect the positionaldisplacement of the nozzle attached to the tip of the swing arm in theabove embodiment, the movement path of the nozzle is limited to the oneon a virtual arc in a horizontal plane. Thus, the position of the nozzleand the presence or absence of the displacement in the space inside thechamber can be uniquely expressed only by a scalar quantity which is thedisplacement amount from the reference position. However, moregenerally, the nozzle is movable to an arbitrary position in the actualspace and a configuration for moving and positioning a positioningobject by an XY moving mechanism is also, for example, conceivable.

Even in such a case, conversion from the position detection result inthe image into the position or the displacement from the referenceposition in the actual space is possible by applying the technicalconcept of the invention. In this case, the displacement can beexpressed as a vector having a direction and a magnitude. Note thatthere are possibly cases where positioning objects located at differentpositions in an actual space appear at the same position in atwo-dimensional image and the position in the actual space cannot beuniquely obtained from the image. Such a problem may be avoided, forexample, by changing the arrangement of the camera.

Further, in the above embodiment, the image of the nozzle included inthe image is detected by pattern matching and the nozzle as the“positioning object” of the invention is the “imaging object” of theinvention. However, the “imaging object” of the invention needs not bethe same as the “positioning object”. Specifically, an object canfunction as the “imaging object” of the invention if it is integrallydisplaced as the positioning object is displaced and the position of thepositioning object is uniquely obtained by detecting the position ofthat object. For example, a marker for position detection may beprovided on the arm having the nozzle attached thereto and this can beused as the “imaging object”. In this case, since the shape of themarker can be freely determined, position detection can be more simplyperformed by setting a shape easily detectable from an image as theshape of the marker.

Further, in the operation of the above embodiment, the nozzle positioncalculation process to which the displacement detecting method accordingto the invention is applied is adopted to detect the positionaldisplacement of the camera 72 and detect the positional displacement ofthe substrate W. However, the invention can be carried out independentlyof these positional displacement detection processes.

Further, for example, the above-mentioned displacement detecting methodusing the nozzle as a positioning object can be implemented by the CPU81 provided in the controller 80 of the substrate processing system 1executing a predetermined control program. Thus, the invention can bedistributed to the user as software for realizing the above process bybeing executed by the CPU 81.

Further, the above embodiment relates to the substrate processing unitfor processing the substrate using the nozzle as the positioning objectof the invention. However, an application range of the displacementdetection technique of the invention is not limited to substrateprocessing. Specifically, various objects effectively acting by beingpositioned at predetermined positions can be used as positioning objectsand applied to techniques in general for detecting displacements of suchpositioning objects.

As the specific embodiment is illustrated and described above, thedisplacement detector may be configured to search, in an image, an areaequivalent to a reference image prepared in advance, for example, incorrespondence with an imaging object and detect the position of theimaging object in the image. Such a searching technique is so-called apattern matching technique and many techniques capable of detectingareas corresponding to a reference image from various images have beenproposed thus far. By utilizing such techniques, the position of theimaging object in the image can be detected with high accuracy.

Further, for example, the storage may be provided which stores arelationship of the position of the imaging object in the image and thecoefficient associated with this position, and the displacement detectormay be configured to obtain a displacement amount of the positioningobject based on the position of the imaging object in the image and therelationship stored in the storage. According to such a configuration,when the position of the imaging object is detected in the image, thedisplacement amount of the positioning object can be immediatelyobtained from the relationship stored in the storage. This eliminatesthe need to obtain the size of the imaging object in the image and theprocess can be simplified.

In this case, the relationship of the position of the imaging object andthe coefficient may be obtained in advance based on a relationship ofthe position and size of the imaging object in images detected from aplurality of images obtained by the imager imaging the imaging objectsuccessively positioned at a plurality of positions by the mover.Further, in the displacement detecting method according to thisinvention, a step of determining the relationship of the position of theimaging object and the coefficient may be performed prior to thedisplacement detecting step, for example, based on the relationship ofthe position and size of the imaging object in images detected from aplurality of images obtained by the imager imaging the imaging objectsuccessively positioned at a plurality of positions by the mover.According to such a configuration, since the coefficient is determinedfrom the images imaged in the actual apparatus, the displacement amountof the positioning object in the actual space inside the apparatus canbe accurately obtained.

On the other hand, the displacement detecting apparatus and displacementdetecting method according to this invention may be, for example,configured to detect the position of the imaging object in the image bysearching, in the image, the area corresponding to the reference imageprepared in advance in correspondence with the imaging object and setthe coefficient according to the size of the detected imaging object.When such a pattern matching technique is used to detect the imagingobject in the image, a ratio of the size of the area corresponding tothe detected imaging object to the size of the reference image can serveas information indicating the size of the imaging object in the image.For example, if it is necessary to enlarge or reduce the reference imagefor the detection of the area by pattern matching, information relatingto an enlargement rate or reduction rate can be used as the informationindicating the size of the imaging object. In this case, the size of theimaging object needs not be calculated.

Further, for example, the displacement detector may be configured todetect the size of the imaging object detected in the image and set thecoefficient based on a detection result. According to such aconfiguration, the size of the imaging object in the image needs to beobtained every time, but it is no longer necessary to perform apreparatory process for obtaining the coefficient beforehand.

Further, the substrate processing apparatus according to the inventionmay further include a determiner for determining whether or not thedisplacement amount with respect to the reference position of the nozzledetected by the displacement detector is larger than a predeterminedallowable displacement amount. According to such a configuration, theprocess can be made different according to the displacement amount ofthe nozzle. For example, if a fluid is discharged from the nozzle onlywhen the displacement amount of the nozzle is within the allowabledisplacement amount, a failure of the process due to the discharge ofthe fluid at an improper position can be prevented.

Further, for example, the nozzle may be provided with a cylindrical partand the displacement detector may be configured to detect a distancebetween both side surfaces of the cylindrical part from the image andset the coefficient according to that detection result. When the nozzleas the imaging object moves within an imaging visual field of theimager, the orientation of the nozzle with respect to the imager mayvary. If the nozzle includes the cylindrical part, a diameter of thecylindrical part expressed by the distance between the both sidesurfaces of the cylindrical part can be utilized as informationindicating the size of the nozzle even if the orientation with respectto the imager varies.

Further, the substrate processing apparatus according to this embodimentmay include a holder for holding a work, a nozzle for discharging andsupplying a fluid to the work, a mover for moving and positioning thenozzle, an imager for imaging an image including the nozzle or an objectas an imaging object, the object displacing integrally with the nozzleas the nozzle is displaced, a displacement detector for detecting theimaging object from the image imaged by the imager and detecting adisplacement of the nozzle based on the position of the imaging objectdetected in the image, and a determiner for determining whether or not adisplacement amount of the nozzle detected by the displacement detectoris larger than a predetermined allowable displacement amount, and thedeterminer may be configured to determine that the displacement amountis larger than the allowable displacement amount when a distance betweenthe position of the imaging object and a predetermined referenceposition in the image is larger than a value obtained by multiplying theallowable displacement amount by a coefficient determined according tothe size of the imaging object in the image.

In the substrate processing apparatus aiming to evaluate a displacementamount of a positioning object based on a magnitude relationship with anallowable displacement amount, it is not a prerequisite to obtain thevalue of the displacement amount of the positioning object itself. Insuch an apparatus, the aim thereof can be achieved by scaling theallowable displacement amount according to the size of the image in theimage and comparing the displacement amount of the imaging object in theimage and the scaled allowable displacement amount instead of convertingthe displacement amount in the image into the displacement amount in theactual space.

This invention can be applied to techniques in general for detectingdisplacements of various objects, which effectively act by beingpositioned at a predetermined position, as positioning objects.

Although the invention has been described with reference to specificembodiments, this description is not meant to be construed in a limitingsense. Various modifications of the disclosed embodiment, as well asother embodiments of the present invention, will become apparent topersons skilled in the art upon reference to the description of theinvention. It is therefore contemplated that the appended claims willcover any such modifications or embodiments as fall within the truescope of the invention.

What is claimed is:
 1. A displacement detecting apparatus, comprising: amover which moves and positions a positioning object; an imager whichimages an image including an imaging object which is the positioningobject or an object displacing integrally with the positioning object asthe positioning object is displaced; and a displacement detector whichdetects the imaging object from the image imaged by the imager anddetects a displacement of the positioning object based on the positionof the imaging object detected in the image, wherein the displacementdetector obtains a displacement amount of the positioning object withrespect to a predetermined reference position from a value obtained bymultiplying a distance between the position of the imaging object andthe reference position in the image by a coefficient determinedaccording to size of the imaging object in the image; further comprisinga storage which stores a relationship of the position of the imagingobject in the image and the coefficient associated with this position,wherein the displacement detector obtains the displacement amount of thepositioning object based on the position of the imaging object in theimage and the relationship stored in the storage, and wherein therelationship of the position of the imaging object and the coefficientis obtained in advance based on a relationship of the position and sizeof the imaging object in images detected from a plurality of imagesobtained by the imager imaging the imaging object successivelypositioned at a plurality of positions by the mover.
 2. The displacementdetecting apparatus according to claim 1, wherein: a reference imagecorresponding to the imaging object is prepared in advance; and thedisplacement detector detects the position of the imaging object in theimage by searching an area equivalent to the reference image in theimage.
 3. The displacement detecting apparatus according to claim 2,wherein the displacement detector sets the coefficient based on a ratioof a size of the area equivalent to the reference image detected in theimage to size of the reference image.
 4. The displacement detectingapparatus according to claim 1, wherein the displacement detector setsthe coefficient based on a detection result of detecting the size of theimaging object in the image.
 5. A substrate processing apparatus,comprising: a holder which holds a work to be processed; a nozzle whichdischarges and supplies a fluid to the work; and the displacementdetecting apparatus according to the claim 1 using the nozzle as thepositioning object.
 6. The substrate processing apparatus according toclaim 5, further comprising a determiner which determines whether or notthe displacement amount with respect to the reference position of thenozzle detected by the displacement detector is larger than apredetermined allowable displacement amount.
 7. The substrate processingapparatus according to claim 5, wherein: a cylindrical part is providedto the nozzle; and the displacement detector detects a distance betweenboth side surfaces of the cylindrical part from the image and sets thecoefficient according to that detection result.
 8. A substrateprocessing apparatus, comprising: a holder which holds a work to beprocessed; a nozzle which discharges and supplies a fluid to the work; amover which moves and positions the nozzle; an imager which images animage including an imaging object which is the nozzle or an objectdisplacing integrally with the nozzle as the nozzle is displaced; adisplacement detector which detects the imaging object from the imageimaged by the imager and detects a displacement of the nozzle based onthe position of the imaging object detected in the image; and adeterminer determines that the displacement amount is larger than anallowable displacement amount when a distance between the position ofthe imaging object and a predetermined reference position in the imageis larger than a value obtained by multiplying the allowabledisplacement amount by a coefficient determined according to a size ofthe imaging object in the image.
 9. The substrate processing apparatusaccording to claim 8, wherein: a cylindrical part is provided to thenozzle; and the displacement detector detects a distance between bothside surfaces of the cylindrical part from the image and sets thecoefficient according to that detection result.
 10. A displacementdetecting method for detecting a displacement of a positioning objectmoved and positioned by a mover, the displacement detecting methodcomprising: imaging an image including an imaging object which is thepositioning object or an object displacing integrally with thepositioning object as the positioning object is displaced; detecting theimaging object from the image; and detecting a displacement of thepositioning object with respective to a predetermined reference positionbased on the position of the imaging object detected in the image,wherein a displacement amount of the positioning object is obtained froma value obtained by multiplying a distance between the position of theimaging object and the reference position in the image by a coefficientdetermined according to size of the imaging object in the image; andfurther comprising, prior to detecting the displacement of thepositioning object, determining a relationship of the position of theimaging object and the coefficient based on a relationship of theposition and size of the imaging object in images detected from aplurality of images obtained by the imager imaging the imaging objectsuccessively positioned at a plurality of positions by the mover. 11.The displacement detecting method according to claim 10, wherein: areference image corresponding to the imaging object is prepared inadvance; the position of the imaging object in the image is detected bysearching an area equivalent to the reference image in the image; andthe coefficient is determined according to the size of the imagingobject detected in the image.
 12. A displacement detecting apparatus,comprising: a mover which moves and positions a positioning object; animager which images an image including an imaging object which is thepositioning object or an object displacing integrally with thepositioning object as the positioning object is displaced; and adisplacement detector which detects the imaging object from the imageimaged by the imager and detects a displacement of the positioningobject based on the position of the imaging object detected in theimage, wherein the displacement detector obtains a displacement amountof the positioning object with respect to a predetermined referenceposition from a value obtained by multiplying a distance between theposition of the imaging object and the reference position in the imageby a coefficient determined according to size of the imaging object inthe image, wherein a reference image corresponding to the imaging objectis prepared in advance; wherein the displacement detector detects theposition of the imaging object in the image by searching an areaequivalent to the reference image in the image, and wherein thedisplacement detector sets the coefficient based on a ratio of a size ofthe area equivalent to the reference image detected in the image to sizeof the reference image.
 13. A substrate processing apparatus,comprising: a holder which holds a work to be processed; a nozzle whichdischarges and supplies a fluid to the work; and a displacementdetecting apparatus comprising: a mover which moves and positions apositioning object; an imager which images an image including an imagingobject which is the positioning object or an object displacingintegrally with the positioning object as the positioning object isdisplaced; and a displacement detector which detects the imaging objectfrom the image imaged by the imager and detects a displacement of thepositioning object based on the position of the imaging object detectedin the image, wherein the displacement detector obtains a displacementamount of the positioning object with respect to a predeterminedreference position from a value obtained by multiplying a distancebetween the position of the imaging object and the reference position inthe image by a coefficient determined according to size of the imagingobject in the image, wherein the positioning object is the nozzle, andfurther comprising a determiner which determines whether or not thedisplacement amount with respect to the reference position of the nozzledetected by the displacement detector is larger than a predeterminedallowable displacement amount.
 14. A substrate processing apparatus,comprising: a holder which holds a work to be processed; a nozzle whichdischarges and supplies a fluid to the work; and a displacementdetecting apparatus comprising: a mover which moves and positions apositioning object; an imager which images an image including an imagingobject which is the positioning object or an object displacingintegrally with the positioning object as the positioning object isdisplaced; and a displacement detector which detects the imaging objectfrom the image imaged by the imager and detects a displacement of thepositioning object based on the position of the imaging object detectedin the image, wherein the displacement detector obtains a displacementamount of the positioning object with respect to a predeterminedreference position from a value obtained by multiplying a distancebetween the position of the imaging object and the reference position inthe image by a coefficient determined according to size of the imagingobject in the image, wherein the positioning object is the nozzle,wherein a cylindrical part is provided to the nozzle; and wherein thedisplacement detector detects a distance between both side surfaces ofthe cylindrical part from the image and sets the coefficient accordingto that detection result.